(When geomancers their Fortuna Major
/ See in the East before the dawn
/ Rise by a path that long remains not dim (Purg. XIX, 4-6) )

This renowned Dante’s tercet was carefully commented on by the first exegetes of The Divine Comedy, who did not explain it allegorically but as actually referring to the divinatory art known as geomancy. They elucidated the geomantic procedure, often providing technical details on its more crucial aspects. Jacopo della Lana, for instance, made clear that it consists in drawing sixteen lines of dots «randomly» («a ventura») which means «without counting the dots» («cença numerare li punti»); moreover, the operation is performed «in l’aurora», for this is the time when digestion is completed, and the limbs («menbri del corpo»), unimpeded («agravadi») by any internal cause, are more receptive to the influences of celestial motions. Jacopo della Lana also pointed out that the human body can be moved by three causes: by an act of volition elicited by a decision of free will; by an act of volition caused by bodily affections due to immoderate wine drinking, eating, etc.; or by a natural inclination subject to the motion of the celestial sphere. Both the first and second cause collide with the geomantic practice, for free choice implies drawing the dots consciously by counting them, while interior bodily passions occur when digestion is still working. The third cause is compatible with geomancy, for geomancy is called «astrologia menore».
Jacopo’s text reaches a significant level of methodological and epistemological complexity. However, it is not an isolated case, for other commentators on Dante, commented extensively on the tercet, elucidating the main steps of the geomantic technique, highlighting its critical points, reflecting on its scientific validity, and giving hints on its origin.
The explanations of Dante’s commentators are only one example among many others which give witness to the cultural importance of geomancy in the Middle Ages. This predictive art seems to have had a preeminent position among the techniques of divination. In fact, the main thirteenth-century thinkers felt the need to take a stance regarding geomancy: Thomas Aquinas, Albert the Great, Bonaventure of Bagnoregio, and Siger of Brabant all of them expressed different positions towards this form of divination, ranging from a detailed inspection of its epistemological status to a straightforward dismissal of it as an art dealing with frivolous things («frivola»). Several ecclesiastical condemnations, among which is the famous Parisian Syllabus issued by the Archbishop Étienne Tempier in 1277, confirm that geomancy was very popular and controversial.
It is difficult to explain why geomancy became so central to the field of medieval divination. It has been said from the Middle Ages onward that unlike astrology, which is regarded as the queen of the predictive sciences, the geomantic technique is a rather easy method to be adopted, neither needing complex instruments, nor requiring abstruse calculations or careful astronomical observations. Yet this simplicity only partly explains the popularity of this art since other divinatory sciences were also easily performed.
Despite its fortune and cultural relevance, scholarly literature on medieval geomancy has thus far been relatively modest if compared with the huge output of studies dedicated to astrology. In the last hundred years there have been few studies on medieval geomancy, and even fewer which have been noteworthy. [...]

In keeping with the current multi-faceted perception of the Middle Ages, the present volume explores medieval geomancy not only in the Latin, but also in the Arabic and Hebrew worlds. Key issues involved in this form of divination are discussed at length by the contributors: the operative method, texts and translations, theological and philosophical reflection, ecclesiastical reactions and condemnations, etc. The comparison with previous scholarship reveals how far research has developed. Several contributors, for instance, provide a philological and textual analysis of Hugh of Santalla’s Ars geomantiae, the Estimaverunt Indi, and the Geomantia attributed to William of Moerbeke, that is of the same treatises that had already been transcribed and studied by Tannery and Charmasson. New conclusions, however, are reached with regard to the manuscript tradition, authorship, and sources of these writings. Old solutions are abandoned. New problems, unseen before, now emerge.
In addition to geomancy, many medieval divinatory sciences, including astrology and magic, are investigated. Indeed geomancy and its peculiarities can only be properly understood if considered in its historical relationship to other forms of prognostication. Therefore, several contributions deal with the debates on divination (epistemological validity of the prediction of future events, astral influence on the diviner, determinism, images, operative nature of divinatory practice, etc.), celestial causality, human free-will, demonic magic, etc.
A specific section of our present book dwells on the Arabic and Hebrew geomantic tradition, analysing it in the wider framework of the divinatory literature in the Eastern civilization. [...]

This volume suggests further lines of such research. Cataloguing and describing all Latin and vernacular geomantic manuscripts, critical editions of unedited texts, identification of the Arabic sources of Latin treatises, a comprehensive history of medieval and modern geomancy, an overall scrutiny of the Arabic, Hebrew and Byzantine tradition – these all are some of the tasks that confront the scholars who intend to enlarge our knowledge of geomancy.